【摘要】 采用浸渍法制备了不同La2O3含量的Pd密偶催化剂.使用低温N2吸附-脱附、X射线衍射、H2程序升温还原、CO化学吸附和X射线光电子能谱等技术考察了La2O3对催化剂性能的影响.模拟汽车尾气条件考察了催化剂上丙烷的转化活性.活性测试结果表明,La2O3的添加能显著提高催化剂对丙烷的转化活性和催化剂的热稳定性.H2-TPR结果表明La2O3的添加降低了催化剂的还原温度,提高了催化剂的氧化还原性能.CO化学吸附和XPS结果表明,La2O3的添加提高了Pd物种的分散,降低了Pd的平均颗粒度.La2O3的最佳添加量为10%.更多还原

【Abstract】 Palladium close-coupled catalysts were prepared by impregnation method with different amounts of La2O3 as a promoter.Low temperature N2 adsorption-desorption,X-ray diffraction,H2-temperature programmed reduction (H2-TPR),CO-chemisorption,and X-ray photoelectron spectroscopy (XPS) were used to characterize the effect of La2O3 on the physicochemical properties of the prepared catalysts.Their catalytic activities toward C3H8 conversion were evaluated using a gas mixture that simulates the emissions from a gasoline engine.The results of catalytic activity indicate that the presence of La2O3 significantly improves catalytic performance and enhances the thermal resistance of the catalysts.H2-TPR results suggest that the addition of La2O3 increases the reductive ability of the catalysts and shifts the reduction temperature to a lower value.The XPS and CO-chemisorption results indicate that doping by La2O3 also improves the dispersion of the Pd species and decreases the mean particle size of palladium.The optimal loading amount of La2O3 is 10%.更多还原